/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: FuncPosition.java,v 1.2.4.1 2005/09/14 20:18:45 jeffsuttor Exp $
 */
package com.sun.org.apache.xpath.internal.functions;

import com.sun.org.apache.xml.internal.dtm.DTM;
import com.sun.org.apache.xml.internal.dtm.DTMIterator;
import com.sun.org.apache.xpath.internal.XPathContext;
import com.sun.org.apache.xpath.internal.axes.SubContextList;
import com.sun.org.apache.xpath.internal.compiler.Compiler;
import com.sun.org.apache.xpath.internal.objects.XNumber;
import com.sun.org.apache.xpath.internal.objects.XObject;

/**
 * Execute the Position() function.
 * @xsl.usage advanced
 */
public class FuncPosition extends Function {
    static final long serialVersionUID = -9092846348197271582L;
    private boolean m_isTopLevel;

    /**
     * Figure out if we're executing a toplevel expression.
     * If so, we can't be inside of a predicate.
     */
    public void postCompileStep(Compiler compiler) {
        m_isTopLevel = compiler.getLocationPathDepth() == -1;
    }

    /**
     * Get the position in the current context node list.
     *
     * @param xctxt Runtime XPath context.
     *
     * @return The current position of the itteration in the context node list,
     *         or -1 if there is no active context node list.
     */
    public int getPositionInContextNodeList(XPathContext xctxt) {

        // System.out.println("FuncPosition- entry");
        // If we're in a predicate, then this will return non-null.
        SubContextList iter = m_isTopLevel ? null : xctxt.getSubContextList();

        if (null != iter) {
            int prox = iter.getProximityPosition(xctxt);

            // System.out.println("FuncPosition- prox: "+prox);
            return prox;
        }

        DTMIterator cnl = xctxt.getContextNodeList();

        if (null != cnl) {
            int n = cnl.getCurrentNode();
            if (n == DTM.NULL) {
                if (cnl.getCurrentPos() == 0)
                    return 0;

                // Then I think we're in a sort.  See sort21.xsl. So the iterator has
                // already been spent, and is not on the node we're processing.
                // It's highly possible that this is an issue for other context-list
                // functions.  Shouldn't be a problem for last(), and it shouldn't be
                // a problem for current().
                try {
                    cnl = cnl.cloneWithReset();
                } catch (CloneNotSupportedException cnse) {
                    throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException(cnse);
                }
                int currentNode = xctxt.getContextNode();
                // System.out.println("currentNode: "+currentNode);
                while (DTM.NULL != (n = cnl.nextNode())) {
                    if (n == currentNode)
                        break;
                }
            }
            // System.out.println("n: "+n);
            // System.out.println("FuncPosition- cnl.getCurrentPos(): "+cnl.getCurrentPos());
            return cnl.getCurrentPos();
        }

        // System.out.println("FuncPosition - out of guesses: -1");
        return -1;
    }

    /**
     * Execute the function.  The function must return
     * a valid object.
     * @param xctxt The current execution context.
     * @return A valid XObject.
     *
     * @throws javax.xml.transform.TransformerException
     */
    public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException {
        double pos = (double) getPositionInContextNodeList(xctxt);

        return new XNumber(pos);
    }

    /**
     * No arguments to process, so this does nothing.
     */
    public void fixupVariables(java.util.Vector vars, int globalsSize) {
        // no-op
    }
}
